:root {
  --bg: #f7f5ef;
  --surface: #ffffff;
  --text: #20251f;
  --muted: #626960;
  --border: #dedfd8;
  --accent: #526b3f;
  --accent-dark: #3d5230;
  --soft: #edf1e8;
  --error: #a33d31;
  --radius: 16px;
  --shadow: 0 12px 35px rgba(32, 37, 31, .08);
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.65;
}
a { color: inherit; }
.container { width: min(1120px, calc(100% - 32px)); margin-inline: auto; }
.site-header { background: rgba(255,255,255,.94); border-bottom: 1px solid var(--border); }
.header-inner { min-height: 68px; display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.brand { font-weight: 800; text-decoration: none; letter-spacing: -.02em; }
nav { display: flex; gap: 22px; }
nav a { text-decoration: none; color: var(--muted); font-size: .95rem; }
nav a:hover { color: var(--text); }
.hero { padding: 58px 0 48px; text-align: center; }
.eyebrow { margin: 0 0 10px; font-size: .78rem; font-weight: 800; letter-spacing: .12em; color: var(--accent); }
h1 { margin: 0; font-size: clamp(2.2rem, 5vw, 4rem); line-height: 1.08; letter-spacing: -.045em; }
.hero-lead { max-width: 680px; margin: 18px auto 34px; color: var(--muted); font-size: 1.08rem; }
.calculator-card { width: min(620px, 100%); margin: 0 auto; padding: 28px; text-align: left; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); }
.calculator-heading h2 { margin: 0; font-size: 1.35rem; }
.calculator-heading p { margin: 5px 0 24px; color: var(--muted); }

.calculator-modes { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; margin: 0 0 22px; padding: 5px; background: var(--soft); border-radius: 12px; }
.mode-button { min-height: 44px; border: 1px solid transparent; border-radius: 9px; background: transparent; color: var(--muted); font: inherit; font-weight: 800; cursor: pointer; }
.mode-button.is-active { background: #fff; color: var(--text); border-color: var(--border); box-shadow: 0 2px 8px rgba(32,37,31,.06); }
.mode-button:focus-visible { outline: 3px solid rgba(82,107,63,.2); outline-offset: 2px; }
.calculator-mode[hidden] { display: none; }
.calculator-note { margin: 22px 0 0; padding: 14px 16px; background: #fff; border: 1px solid var(--border); border-radius: 11px; color: var(--muted); font-size: .9rem; }
.field { margin-bottom: 20px; }
label { display: block; margin-bottom: 8px; font-weight: 700; }
.input-unit { display: flex; align-items: center; border: 1px solid #cfd2c9; border-radius: 11px; background: #fff; overflow: hidden; }
.input-unit:focus-within { outline: 3px solid rgba(82,107,63,.15); border-color: var(--accent); }
.input-unit input { width: 100%; border: 0; outline: 0; padding: 14px 15px; font: inherit; color: var(--text); background: transparent; }
.input-unit span { padding: 0 15px; color: var(--muted); font-weight: 700; }
.field-help { margin: 7px 0 0; color: var(--muted); font-size: .86rem; }
.field-error { min-height: 0; margin: 5px 0 0; color: var(--error); font-size: .86rem; }
.advanced { margin: 8px 0 22px; border-top: 1px solid var(--border); padding-top: 16px; }
.advanced summary { cursor: pointer; font-weight: 700; color: var(--accent-dark); }
.advanced-body { padding-top: 18px; }
.primary-button, .secondary-button {
  width: 100%; min-height: 50px; border: 0; border-radius: 11px; font: inherit; font-weight: 800; cursor: pointer;
}
.primary-button { background: var(--accent); color: #fff; }
.primary-button:hover { background: var(--accent-dark); }
.result { margin-top: 24px; border-radius: 14px; background: var(--soft); padding: 24px; text-align: center; }
.result-label { margin: 0; font-size: .75rem; font-weight: 800; letter-spacing: .1em; color: var(--accent-dark); }
.result h3 { margin: 5px 0 0; font-size: clamp(2.6rem, 8vw, 4.2rem); line-height: 1; letter-spacing: -.05em; }
.result-main-label { margin: 5px 0 20px; color: var(--muted); }
.result-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.result-grid > div { background: rgba(255,255,255,.75); border: 1px solid rgba(82,107,63,.12); border-radius: 10px; padding: 12px; }
.result-grid strong, .result-grid span { display: block; }
.result-grid strong { font-size: 1.3rem; }
.result-grid span { color: var(--muted); font-size: .85rem; }
.result-sentence { color: var(--muted); font-size: .9rem; }
.result-actions { display: flex; align-items: center; gap: 10px; }
.secondary-button { background: #fff; border: 1px solid var(--border); color: var(--text); }
.text-button { border: 0; background: transparent; color: var(--muted); cursor: pointer; font: inherit; padding: 12px; }
.content-section { padding: 18px 0 80px; }
.content-narrow { width: min(760px, 100%); margin-inline: auto; }
.content-narrow h2 { margin-top: 44px; font-size: 1.55rem; line-height: 1.25; }
.formula-box { background: #fff; border: 1px solid var(--border); border-radius: 12px; padding: 8px 18px; }
.related-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.related-grid a { background: #fff; border: 1px solid var(--border); border-radius: 11px; padding: 15px; text-decoration: none; font-weight: 700; }
.site-footer { background: #20251f; color: #eef0eb; padding: 40px 0 20px; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr; gap: 30px; }
.footer-grid p { color: #bfc5bc; max-width: 420px; }
.footer-grid > div:last-child { display: grid; gap: 8px; align-content: start; }
.footer-grid a { color: #eef0eb; text-decoration: none; }
.footer-bottom { margin-top: 30px; padding-top: 18px; border-top: 1px solid #3b4139; color: #bfc5bc; font-size: .86rem; }
@media (max-width: 700px) {
  .header-inner { min-height: 60px; }
  nav { gap: 12px; }
  nav a:nth-child(2), nav a:nth-child(3) { display: none; }
  .hero { padding: 48px 0 34px; }
  .calculator-card { padding: 22px 18px; }
  .related-grid, .footer-grid { grid-template-columns: 1fr; }
  .result-actions { flex-direction: column; }
  .secondary-button { width: 100%; }
}

.menu-toggle { display: none; border: 1px solid var(--border); background: #fff; color: var(--text); border-radius: 9px; padding: 8px 11px; font: inherit; font-weight: 700; cursor: pointer; }
.mobile-menu { display: none; }
.estimate-note { margin-top: 40px; padding: 20px 22px; background: var(--soft); border: 1px solid #d9e1d2; border-radius: 12px; }
.estimate-note h2 { margin-top: 0; }
.estimate-note p { margin-bottom: 0; }
.comparison-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: 12px; background: #fff; }
.comparison-table { width: 100%; border-collapse: collapse; min-width: 430px; }
.comparison-table th, .comparison-table td { padding: 13px 15px; text-align: right; border-bottom: 1px solid var(--border); }
.comparison-table th:first-child, .comparison-table td:first-child { text-align: left; }
.comparison-table th { font-size: .86rem; color: var(--muted); background: #fafaf7; }
.comparison-table tr:last-child td { border-bottom: 0; }
.comparison-table tr.is-current td { font-weight: 800; background: var(--soft); }
@media (max-width: 700px) {
  .menu-toggle { display: block; }
  .desktop-nav { display: none; }
  .mobile-menu { background: #fff; border-bottom: 1px solid var(--border); padding: 8px 16px 14px; }
  .mobile-menu a { display: block; padding: 10px 0; text-decoration: none; font-weight: 700; }
  .mobile-menu[hidden] { display: none; }
  .mobile-menu:not([hidden]) { display: block; }
  .hero { padding: 42px 0 30px; }
}

.brand-logo { display: inline-flex; align-items: center; text-decoration: none; }
.brand-logo img { display: block; width: 228px; height: auto; }
.footer-brand { display: inline-flex; margin-bottom: 10px; }
.footer-brand img { display: block; width: 228px; height: auto; filter: none; }
.footer-contact a { color: #fff; text-decoration: underline; text-underline-offset: 2px; }
.inline-link { color: var(--accent-dark); font-weight: 750; text-underline-offset: 3px; }
.related-grid a { display: block; }
.related-grid a span { display: block; margin-top: 5px; color: var(--muted); font-size: .9rem; font-weight: 500; }
.faq-list { display: grid; gap: 10px; }
.faq-list details { background: #fff; border: 1px solid var(--border); border-radius: 12px; padding: 0 17px; }
.faq-list summary { cursor: pointer; padding: 16px 2px; font-weight: 750; }
.faq-list p { margin: 0 2px 17px; color: var(--muted); }
.next-tool { margin-top: 48px; padding: 24px; background: #fff; border: 1px solid var(--border); border-radius: 14px; }
.next-tool h2 { margin-top: 0; }
.primary-link { display: inline-flex; background: var(--accent); color: #fff; text-decoration: none; border-radius: 10px; padding: 12px 16px; font-weight: 800; }
@media (max-width: 700px) {
  .brand-logo img { width: 190px; }
  .desktop-nav { display: none !important; }
  .menu-toggle { display: inline-flex !important; align-items: center; justify-content: center; }
  .mobile-menu { display: block; }
  .mobile-menu[hidden] { display: none !important; }
  .footer-brand img { width: 205px; }
}

/* Phase 2 v0.4 refinements */
.site-header { position: relative; z-index: 20; }
.header-inner { min-height: 74px; }
.brand-logo img { width: 214px; }
.menu-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-width: 104px;
  min-height: 42px;
  padding: 9px 14px;
  border: 1px solid #cfd2c9;
  border-radius: 10px;
  background: #fff;
  color: var(--text);
  font: inherit;
  font-size: .95rem;
  font-weight: 800;
  line-height: 1;
  cursor: pointer;
}
.menu-icon { font-size: 1.15rem; line-height: 1; }
.desktop-nav { display: flex; align-items: center; gap: 24px; }
.desktop-nav a { white-space: nowrap; }
.content-narrow > h1 { margin-bottom: 16px; }
.content-narrow > p { color: #4f554f; }
.reverse-calculator { margin: 28px 0 42px; }
.reverse-calculator .calculator-heading p { margin-bottom: 22px; }
.reverse-result { margin-top: 24px; }
.faq-section { margin-top: 52px; }
.faq-list details { overflow: hidden; box-shadow: 0 2px 10px rgba(32,37,31,.03); }
.faq-list summary { background: #fff; }
.faq-list details[open] summary { border-bottom: 1px solid var(--border); background: #fafaf7; }
.faq-list p { padding: 0 0 18px; margin: 16px 2px 0; }
.footer-grid {
  grid-template-columns: minmax(0, 1.7fr) minmax(150px, .8fr) minmax(150px, .8fr);
  gap: 48px;
  align-items: start;
}
.footer-grid > div { min-width: 0; }
.footer-grid > div:not(:first-child) { display: grid; gap: 9px; align-content: start; }
.footer-grid > div > strong { color: #fff; margin-bottom: 3px; }
.footer-brand img { width: 205px; height: auto; }
.footer-grid p { margin: 14px 0 0; }
.footer-contact { margin-top: 14px !important; }
.footer-bottom { display: flex; justify-content: space-between; gap: 20px; }

@media (max-width: 760px) {
  .container { width: min(100% - 28px, 1120px); }
  .header-inner { min-height: 64px; }
  .brand-logo img { width: 178px; }
  .desktop-nav { display: none !important; }
  .menu-toggle { display: inline-flex !important; }
  .mobile-menu { display: block; padding: 8px 14px 14px; background: #fff; border-bottom: 1px solid var(--border); box-shadow: 0 8px 18px rgba(32,37,31,.06); }
  .mobile-menu[hidden] { display: none !important; }
  .mobile-menu a { display: block; padding: 12px 10px; border-radius: 8px; font-weight: 750; text-decoration: none; }
  .mobile-menu a:hover, .mobile-menu a:focus { background: var(--soft); }
  .content-section { padding-top: 12px; }
  .content-narrow h2 { margin-top: 36px; }
  .calculator-card { padding: 21px 17px; }
  .footer-grid { grid-template-columns: 1fr; gap: 28px; }
  .footer-grid > div:not(:first-child) { display: grid; }
  .footer-bottom { display: block; }
  .footer-bottom span { display: inline; }
  .comparison-wrap { margin-inline: 0; }
}


/* Phase 2 v0.5: focused calculator directory, guide and footer */
.lead-text { color: #4f554f; font-size: 1.08rem; margin: 14px 0 28px; }
.content-meta { font-size: .88rem; color: #666c65 !important; margin: -10px 0 28px !important; padding-left: 12px; border-left: 3px solid #d9e1d2; }
.calculator-directory { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin: 28px 0 42px; }
.tool-card, .guide-feature { display: block; background: #fff; border: 1px solid var(--border); border-radius: 16px; padding: 22px; text-decoration: none; box-shadow: 0 4px 18px rgba(32,37,31,.04); }
.tool-card:hover, .guide-feature:hover { border-color: #c7d0bf; transform: translateY(-1px); }
.tool-card .tool-number { display: inline-flex; align-items: center; justify-content: center; width: 36px; height: 28px; border-radius: 99px; background: var(--soft); color: var(--accent-dark); font-size: .78rem; font-weight: 850; letter-spacing: .05em; }
.tool-card h2 { margin: 16px 0 8px; font-size: 1.28rem; }
.tool-card p, .guide-feature p { color: var(--muted); margin: 0 0 15px; }
.tool-link { color: var(--accent-dark); font-weight: 800; }
.choice-list { display: grid; gap: 10px; margin: 20px 0 30px; }
.choice-list p { margin: 0; background: #fff; border: 1px solid var(--border); border-radius: 11px; padding: 14px 16px; }
.guide-feature { margin: 24px 0 36px; padding: 28px; }
.guide-feature h2 { margin: 8px 0 10px; font-size: 1.6rem; }
.supporting-guide { margin: 22px 0 0; padding: 15px 18px; background: #fff; border: 1px solid var(--border); border-radius: 11px; }
.contact-card { margin: 28px 0 36px; padding: 25px; background: var(--soft); border: 1px solid #d9e1d2; border-radius: 15px; }
.contact-label { margin: 0 0 4px; color: var(--accent-dark); font-size: .75rem; font-weight: 850; letter-spacing: .12em; }
.contact-email { display: inline-block; font-size: clamp(1.2rem, 4vw, 1.65rem); font-weight: 850; color: var(--text); overflow-wrap: anywhere; }
.contact-card p:last-child { margin-bottom: 0; color: var(--muted); }
.footer-about p strong { color: #fff; }
.site-footer { margin-top: 20px; }
.footer-brand img { max-width: 100%; }
@media (max-width: 850px) { .calculator-directory { grid-template-columns: 1fr; } }
@media (max-width: 760px) { .guide-feature { padding: 21px; } .tool-card { padding: 19px; } .footer-grid { gap: 30px; } .footer-about p { max-width: none; } }

/* Phase 2 v0.6: guide article media and focused homepage content */
.guide-hero-image { margin: 26px 0 34px; border: 1px solid var(--border); border-radius: 18px; overflow: hidden; background: #fff; box-shadow: 0 6px 24px rgba(32,37,31,.05); }
.guide-hero-image img { display: block; width: 100%; height: auto; }
.guide-index-card { display: grid; grid-template-columns: minmax(220px,.72fr) minmax(0,1.28fr); gap: 24px; align-items: stretch; margin: 28px 0 42px; padding: 0; overflow: hidden; }
.guide-index-card .guide-card-image { min-height: 220px; background: #f0f3ec; }
.guide-index-card .guide-card-image img { width: 100%; height: 100%; object-fit: cover; display: block; }
.guide-index-card .guide-card-copy { padding: 26px 26px 26px 0; }
.read-more { display: inline-flex; margin-top: 12px; padding: 11px 15px; border-radius: 9px; background: var(--accent); color: #fff; font-weight: 800; text-decoration: none; }
.home-topic-grid { display: grid; grid-template-columns: repeat(2,1fr); gap: 14px; margin: 24px 0 8px; }
.home-topic-card { background: #fff; border: 1px solid var(--border); border-radius: 13px; padding: 19px; }
.home-topic-card h3 { margin: 0 0 8px; font-size: 1.08rem; }
.home-topic-card p { margin: 0; color: var(--muted); }
.home-checklist { margin: 18px 0 0; padding-left: 20px; }
.home-checklist li { margin: 8px 0; }
@media (max-width: 760px) { .guide-index-card { grid-template-columns: 1fr; } .guide-index-card .guide-card-image { min-height: 170px; } .guide-index-card .guide-card-copy { padding: 0 21px 23px; } .home-topic-grid { grid-template-columns: 1fr; } }

/* Phase 3 v0.7: mobile comparison tables and calculator polish */
.input-unit input[aria-invalid="true"] { box-shadow: inset 0 0 0 2px rgba(163,61,49,.18); }
.comparison-table { min-width: 0; table-layout: fixed; }
.comparison-table th, .comparison-table td { overflow-wrap: anywhere; }
@media (max-width: 760px) {
  .comparison-wrap { overflow-x: hidden; }
  .comparison-table { width: 100%; }
  .comparison-table th, .comparison-table td { padding: 11px 8px; font-size: .88rem; line-height: 1.35; }
  .comparison-table th:first-child, .comparison-table td:first-child { width: 24%; }
  .comparison-table th:not(:first-child), .comparison-table td:not(:first-child) { width: 38%; }
}


/* Phase 4: accessible breadcrumb navigation */
.breadcrumbs{display:flex;align-items:center;flex-wrap:wrap;gap:.55rem;margin:0 0 1.35rem;font-size:.88rem;color:#657066;line-height:1.5}
.breadcrumbs a{color:#4d6f3d;text-decoration:none;font-weight:600}
.breadcrumbs a:hover,.breadcrumbs a:focus-visible{text-decoration:underline}
.breadcrumbs span[aria-current="page"]{color:#59625b}
.breadcrumbs span[aria-hidden="true"]{color:#9aa29c}
@media (max-width:700px){.breadcrumbs{font-size:.8rem;margin-bottom:1rem;gap:.4rem}}


/* Phase 4 Step 6 v1.4: accessibility, focus visibility and motion preferences */
.skip-link {
  position: absolute;
  left: 16px;
  top: -60px;
  z-index: 100;
  padding: 10px 14px;
  border-radius: 9px;
  background: var(--text);
  color: #fff;
  font-weight: 800;
  text-decoration: none;
}
.skip-link:focus { top: 12px; }
:focus-visible {
  outline: 3px solid #35552d;
  outline-offset: 3px;
}
.menu-toggle:focus-visible, .primary-button:focus-visible, .secondary-button:focus-visible, .text-button:focus-visible, .primary-link:focus-visible {
  outline-offset: 3px;
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    scroll-behavior: auto !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Phase 6 Step 7: keep the primary navigation usable on narrow/tablet and mobile viewports. */
@media (max-width: 1024px) {
  .desktop-nav { display: none !important; }
  .menu-toggle { display: inline-flex !important; align-items: center; justify-content: center; }
  .mobile-menu { display: block; padding: 8px 14px 14px; background: #fff; border-bottom: 1px solid var(--border); box-shadow: 0 8px 18px rgba(32,37,31,.06); }
  .mobile-menu[hidden] { display: none !important; }
  .mobile-menu a { display: block; padding: 12px 10px; border-radius: 8px; font-weight: 750; text-decoration: none; }
  .mobile-menu a:hover, .mobile-menu a:focus { background: var(--soft); }
}